Preparation and characterization of Ceftazidime loaded electrospun silk fibroin/gelatin mat for wound dressing

Fabrication of Ceftazidime (CTZ) loaded silk fibroin/gelatin (SF/GT) nanofibers (NFs) without the loss of structure and bioactivity of CTZ was demonstrated by electrospinning method. The structure, morphology and mechanical properties of the electrospun SF/GT nanofibrous mats were characterized using FT-IR, SEM and DSC. The drug release profile of different electrospun fibers was analyzed using spectrophotometric method, and also diffusion method was applied to assess the antibacterial effect of NFs. Cell viability was evaluated by MTT assay. The results show that the average diameter of drug loaded NFs at the optimum polymer to drug feeding ratio (10:1) was 276.55±35.8 nm, while increasing the feeding ratio to 1:1 increases the average diameter to 825.02±70.3 nm. FT-IR of drug loaded NFs was revealed that CTZ was successfully encapsulated into NFs while viability study approved cytocompatibility of SF/GT NFs. CTZ was released from NFs during 6 h, and formation of inhibition zone in diffusion test demonstrated the antibacterial effect of drug loaded NFs. Altogether, the CTZ loaded SF/GT NFs can improve the drug effectiveness particularly in the prevention of post-surgical adhesions and infections for wound dressing.     

EDC/NHS crosslinked electrospun regenerated tussah silk fibroin nanofiber mats

The tussah silk fibroin (TSF) nanofibers with 611 nm diameters were prepared by electrospinning with the solvent hexafluoroisopropanol (HFIP). And then, the TSF nanofibers were crosslinked by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide/N-Hydroxysuccinimide (EDC/NHS) crosslinking agent. The morphology and microstructure of the crosslinked TSF nanofibers were characterized by scanning electron microscopy (SEM), Fourier transforms infrared analysis (FTIR), X-ray diffraction, Instron electronic strength tester, and cell culture. After treatment with EDC/NHS crosslinking agent, the TSF nanofibers swelled and its average diameter increased from 611 to 841 nm. FTIR and X-ray diffraction results demonstrated that random coil, ??-helix, and ??-sheet co-existed in the TSF nanofiber mats, but the content of ??-sheet increased from 25.26 to 45.34 %, and the random coil content decreased from 32.47 to 24.94 %. Compared with the electrospun pure TSF nanofiber mats, the crosslinked TSF nanofiber mats exhibited a lower breaking tenacity and initial modulus, which were 5.51 MPa and 9.86 MPa, respectively. At the same time, the extension at break of the crosslinked TSF nanofiber achieved 109.38 %. In cell culture evaluation, the crosslinked TSF nanofibers were found to support cell adhesion and spreading fibroblast L373 and bone marrow mesenchymal stem cells (BMSCs), which had potential utility in a range of tissue engineering.     

Surface modification of silk fibroin nanofibrous mat with dextran for wound dressing

In this study, we examined the effects of a dextran-modified silk fibroin nanofibrous mat (D-SFNM) on wound healing. To increase the hydrophilicity of silk fibroin (SF), the SF nanofibrous mat (SFNM) was modified with oxidized dextran. The D-SFNM absorbed water faster than the SFNM, and the swelling ratio was increased by approximately 80 % compared with the SFNM. An in vitro cell (NIH3T3) test revealed that fewer cells attached to the D-SFNM than the SFNM, but the proliferation of cells was not significantly affected by the presence of dextran. An in vivo wound healing test with mice indicated that the D-SFNM resulted in a good wound recovery effect similar to a commercial wound dressing material. The increased hydrophilicity of the D-SFNM might balance the moist environment at the wound site, which improves the wound healing compared with the SFNM.     

Metal ion adsorbability of electrospun wool keratose/silk fibroin blend nanofiber mats

In this study, electrospun wool keratose (WK)/silk fibroin (SF) blend nanofiber was prepared and evaluated as a heavy metal ion adsorbent which can be used in water purification field. The WK, which was a soluble fraction of oxidized wool keratin fiber, was blended with SF in formic acid. The electrospinnability was greatly improved with an increase of SF content. The structure and properties of WK/SF blend nanofibers were investigated by SEM, FTIR, DMTA and tensile test. Among various WK/SF blend ratios, 50/50 blend nanofiber showed an excellent mechanical property. It might be due to some physical interaction between SF and WK molecules although FTIR result did not show any evidence of molecular miscibility. As a result of metal ion adsorption test, WK/SF blend nanofiber mats exhibited high Cu²⁺ adsorption capacity compared with ordinary wool sliver at pH 8.5. It might be due to large specific surface area of nanofiber mat as well as numerous functional groups of WK. Consequently, the WK/SF blend nanofiber mats can be a promising candidate as metal ion adsorption filter.     

Application of electrospun silk fibroin nanofibers as an immobilization support of enzyme

Silk fibroin (SF) nanofibers were prepared by electrospinning and their application as an enzyme immobilization support was attempted. By varying the concentration of SF dope solution the diameter of SF nanofiber was controlled. The SF nanofiber web had high capacity of enzyme loading, which reached to 5.6 wt%. The activity of immobilizedα-chymotrypsin (CT) on SF nanofiber was 8 times higher than that on silk fiber and it increased as the fiber diameter decreased. Sample SF8 (ca. 205 nm fiber diameter) has excellent stability at 25°C by retaining more than 90 % of initial activity after 24 hours, while sample SF11 (ca. 320 nm fiber diameter) shows higher stability in ethanol, retaining more than 45% of initial activity. The formation of multipoint attachment between enzyme and support might increase the stability of enzyme. From these results, it is expected that the electrospun SF nanofibers can be used as an excellent support for enzyme immobilization.     

Antimicrobial gelatin nanofibers containing silver nanoparticles

Gelatin is one of the most promising biomaterials due to its excellent biocompatibility and biodegradability. In order to improve the antimicrobial activity of gelatin, gelatin nanofibers containing silver nanoparticles were prepared by electrospinning gelatin/AgNO₃/formic acid system, followed by UV irradiation. They were characterized by UV-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis. It was observed that the silver nanoparticles, which presented quasi-sphere shaped and 9–20 nm average diameters, were generated on the surface of the gelatin nanofibers. The size of the silver particles can be adjusted by changing the content of AgNO₃. With increasing the amount of AgNO₃, the average diameters of fibers decreased. The gelatin-Ag nanocomposites were found effective against Staphylococcus aureus and Pseudomonas aeruginosa. From these results, it is expected that the electrospun antimicrobial gelatin nanofiber mat can be used as an excellent wound dressing.     

Development and characterization of multifunctional electrospun ferric oxide-gelatin-glycerol nanofibrous mat for wound dressing applications

In this study, we developed optimal multifunctional electrospun wound dressings possessing an antibacterial activity and rich in iron, a vital trace element for cell growth. Therefore, synthetic ferric oxide nanoparticles (α-Fe₂O₃ NPs) were ultrasonically dispersed into preheated gelatin-glycerol solution. A variety of techniques (X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal analysis (DTA), in-vitro swelling-degradation studies and antibacterial tests) were used to characterize the electrospun mats. The results highlight that α-Fe₂O₃ NPs could be successfully dispersed into the electrospun gelatin nanofibers. The electrospun ferric oxide-gelatin-glycerol nanofibrous mats revealed free beads nanofibers with appropriated swelling-degradation behavior. It was observed that addition of α-Fe₂O₃ NPs enhanced the antibacterial activity of electrospun mats against positive and negative bacteria.     

Functional electrospun cellulosic nanofiber mats for antibacterial bandages

Functionalization of cellulosic nanofibers was established to develop antibacterial bandages. The functionalization was conducted through preparation of carboxymethyl cellulose (CMC) containing different metal nanoparticles (MNPs) such as copper nanoparticles (CuNPs), iron nanoparticles (FeNPs) and zinc nanoparticles (ZnNPs). Fourier Transform Infrared spectroscopy was used to characterize CMC containing MNPs and scanning electron microscopy coupled with high energy dispersive X-ray (SEM-EDX) to study the surface morphology of CMC with and without MNPs. Furthermore, back scattering electron detector was used to show the position of metal nanoparticles on the microcrystalline CMC. In addition, UV-visible spectroscopy was used to confirm MNPs formation. Nanofiber mats of CMC containing MNPs were synthesized using electrospinning technique. Surface morphology of electrospun CMC containing MNPs was characterized using SEM. The obtained data revealed that elctrospun CMC nanofibers containing MNPs were smooth and uniformly distributed without bead formation. The average fiber diameters were in the range of 150 to 200 nm and the presence of MNPs in the nanofiber did not affect the size of the electrospun nanofiber diameter. Transmission electron microscopy (TEM) images displayed that MNPs were existed inside and over the surface of the electrospun nanofibers without any agglomeration. The average particle diameters of MNPs were 29-39 nm for ZnNPs, 23-27 nm for CuNPs and 22-26 nm for FeNPs. Moreover, Water uptake of electrospun nanofiber mats and the release of MNPs from nanofibers were evaluated. Nevertheless, electrospun CMC nanofibers containing MNPs had an excellent antibacterial activity against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus.     

Cellulose nanofiber-reinforced silk fibroin composite film with high transparency

We successfully prepared optically transparent silk fibroin-cellulose nanofiber (CN) composite films from solvent casting using a stable CN suspension in an aqueous silk fibroin solution. The transmittance of the silk fibroin composite films was observed by a UV-visible spectrophotometer. The secondary structural change of the silk fibroin caused by the incorporation of CNs was characterized using Fourier transform infrared spectroscopy. A tensile test was carried out to investigate the mechanical properties. The results showed that the composite film exhibited visible-light transmittance of 75 %, and its mechanical strength and Young’s modulus were increased by 44 % and 35 %, respectively, as compared to a neat silk fibroin film.     

Preparation of electrospun silk fibroin/Cellulose Acetate blend nanofibers and their applications to heavy metal ions adsorption

Silk fibroin (SF)/Cellulose Acetate (CA) blend nanofibrous membranes were prepared by electrospinning and their heavy metal absorbabilities were examined in an aqueous solution after ethanol treatment. The electrospun nanofibrous membranes were comprised of randomly oriented ultrafine fibers of 100–600 nm diameters. As a result of field emission electron microscope (FEEM), the anti-felting properties of the blend nanofibrous membranes were markedly improved after treatment with 100 % ethanol when SF was blended with CA. Metal ion adsorption test was performed with Cu²⁺ as a model heavy metal ion in a stock solution. The SF/CA blend nanofiber membranes showed higher affinity for Cu²⁺ in an aqueous solution than pure SF and pure CA nanofiber membranes. Especially, the blend nanofibrous membranes with 20 % content of CA had an exceptional performance for the adsorption of Cu²⁺, and the maximum milligrams per gram of Cu²⁺ adsorbed reached 22.8 mg/g. This indicated that SF and CA had synergetic effect. Furthermore, the parameters affecting the metal ions adsorption, such as running time and initial concentration of Cu²⁺, had been investigated. The results showed that the adsorption of the Cu²⁺ sharply increased during the first 60 min, the amount of metal ions adsorbed increased rapidly as the initial concentration increased and then slope of the increase decreased as the concentration further increased. This study provides the relatively comprehensive data for the SF/CA blend nanofibrous membranes application to the removal of heavy metal ion in wastewater.     

Composite wound dressing for drug release

Present study is focused on the preparation of two layers composite wound dressing for drug release. The outer layer is made of hydrogel which contains of drug and the core layer is made of fabric. The two layers structure of composite dressing is formed by grafting of polyacrylamide-co-acrylic acid hydrogel on cotton fabric using ammonium per sulphate (APS) as chemical initiator and polyethylene glycol (PEG) as crosslinker. The major factors affecting graft copolymerization of hydrogel on cotton fabric are optimized by varying concentration of monomers & initiator, reaction temperature and addition time of crosslinker. Maximum grafting of hydrogel is obtained at 5 % (w/v) APS and 15 % acrylamide/acrylic acid (1:1 w/w ratio) concentration. The FTIR spectra of composite dressing shows characteristics peak of acrylic acid and acrylamide. The composite wound dressing material is loaded with model drug bovine serum albumin (BSA) and drug release behaviour is studied at different pH. The dressing shows drug release in different pH with maximum release of drug in acidic medium.     

Simultaneous application of silver nanoparticles with different crease resistant finishes

Textiles, especially those made of natural fibers, are suitable medium for the growth of microorganisms which causes disease transmission, stink, colorful spots, and reduction in fabric strength. This research focuses on the antimicrobial finishing of cotton fabrics using colloidal solution of silver nanoparticles. Due to the difficulties of adding a new step to the finishing process of cotton textiles, efforts have been made to combine the antimicrobial treatment with the conventional finishing processes. For this purpose two chemical finishes of Fixapret ECO as a crosslinking agent and Cellofix ME as a resin former have been used in anti crease finishing of cotton fabric and their effects were evaluated. The properties of the samples have been investigated by measuring the resistant of samples against bacteria, crease recovery angle, abrasion, and washing fastness. The results showed that treated samples by pad-dry method have the best antibacterial effect with a direct relation between the increase in drying temperature and antibacterial properties. However, the washing and abrasion fastness were not at the acceptable level. Co-application of the colloidal solution of silver nanoparticles with the crease resistant materials improved both fastness properties while at the same time limited the direct contact between the nanoparticles and the bacteria so the antibacterial efficiency was reduced. Subsequently, it was concluded that the antibacterial finishing method should be selected according to the end uses. In addition, antibacterial treatment could be one of the multi-purpose finishes for cotton fabric.     

Montelukast incorporated poly(methyl vinyl ether-co-maleic acid)/poly(lactic-co-glycolic acid) electrospun nanofibers for wound dressing

The aim of the present study was to prepare nanofibers loaded with montelukast, a cysteinyl leukotrienes (CysLTs) inhibitor, with anti-inflammatory properties effective on wound healing. Polymeric nanofibers containing montelukast were spun by electrospinning method using different ratios of the blend of two biodegradable polymers of poly(methyl vinyl etherco-maleic acid) (PMVEMA) and poly(lactic-co-glycolic acid) (PLGA) at the total polymer concentration of 37 %, the distance of the needle to rotating screen of 19 cm, the voltage of 12 Kv and the rate of injection of 0.2 ml/h. The ratio of two polymers in the blend and the concentration of montelukast were optimized based on the diameter of the nanofibers, drug loading percent and release efficiency by a full factorial design. The morphology, diameter and diameter distribution of the nanofibers were studied by scanning electron microscopy (SEM). Drug loading percent in the nanofibers was determined by extracting the loaded drug from a specific surface of the nanofibers which was subsequently analyzed spectrophotometrically. The drug release rate from the nanofibers was studied in phosphate buffer solution (pH 7.4) containing 0.5 % Tween 20 at predetermined time intervals until 10 days. The cytotoxicity of the designed nanofibers was evaluated on mouse fibroblast cells using trypan blue method, their platelet adherence property was quantified by measuring the lactate dehydrogenase (LDH) activity and confirmed by SEM micrographs. The optimized ratio of PLGA/PMVEMA was 3:1 with the total concentration of polymers as 37 % loaded with 30 % of montelukast produced nanofibers with a diameter of 157.6 nm, drug loading percent of 43.7 % and release efficiency of 75 % after 10 days. The cell viability was similar in nanofibers and the negative control group. The platelets adhesion to the nanofibers was more than the negative control group (p<0.05).     

Fabrication of silk fibroin/eggshell nanofiber membranes for facemasks

We report our study on fabrication of soluble eggshell membrane (SESM) and silk fibroin (SF) nanofibers composite (SF/SESM) for facemasks by electrospinning. Biocompatibility of the SF and SESM, determined from hydrophilicity results, is exploited in SF/SESM nanocomposite for facemask application. The SF/SESM nanocomposites were prepared in different ratios of SF and SESM. The samples were characterized by scanning electron microscopy (SEM), FTIR and water droplet adsorption tests conducted via water contact angle (WCA) and water droplet diffusion. The results revealed that addition of SESM has insignificant effect on the electrospinnability of SF nanofibers in the studied ratios. The SEM results depicted regular morphology of the nanofibers except increase in nanofiber diameter with addition of SESM. The FTIR results confirmed respective peaks of SF and SESM in SF/SESM nanocomposite. WCA of the nanofibers decreased with addition of SESM such that for SF/SESM30, 30 % SESM, it reduced to 0 ° from 101 ° for pure SF nanofibers. The research results demonstrate SF/SESM30 nanocomposite as optimum ratio of SF and SESM for facemasks and other biomedical applications.     

Mechanism of silk fibroin scaffolds with oriented multichannels and its cytocompatibility

As a biomaterial, besides excellent biocompatibility and biodegradability, suitable macropores and pores structure should be provided to guide cell extension and migration. In present study, the silk fibroin (SF) scaffold with uniaxial channels was prepared by directional temperature field freezing technique. The average pore diameter, pore density and porosity of the scaffold with oriented channels are ～128.7 µm, ～158 mm^?2 and ～91.4 %, respectively. By controlling of the temperature gradient direction, the oriented multichannels of the scaffolds were formed in longitudinal easily. In process of the scaffolds fabrication, the directional growth of ice crystal could shear and draft to the silk fibroin molecule segments, which resulted in the new crystal nucleus formation in new zone and increase of β-sheet components in the scaffolds. In vitro, L929 cells were seeded on the scaffolds with oriented channels to evaluate the effect on cell behavior. Cell viability, adhesion and morphology were determined by methyl thiazolyl tetrazolium, confocal microscope and scanning electron microscope. The results showed that the cells anchored on the oriented channels, spread along the direction of the channels and hold a higher viability on the scaffolds with oriented channels. These new oriented multichannel scaffold could guide the adhesion and proliferation of L929 cells, which hold a potential in tissue engineering.     

Fabrication of silk fibroin based three dimensional scaffolds for tissue engineering

Herein we report successful synthesis of silk fibroin (SF) three dimensional scaffolds (SF 3D-scaffold) from SF sponge and SF nanofibers. Both the nanofibers and sponge were prepared from Bombyx mori fibroin. The SF 3D-scaffold was prepared by electrospinning the fibroin nanofibers over the sponge. Surface morphology was determined by scanning electron microscopy (SEM), while nanofiber diameter and pore size were measured using imageJ software. Effect of spinning time on the pore size and cell adhesion was determined. Average diameter of the SF nanofibers was measured to be 320 nm and pore size was found to reduce with increasing spinning time, such that, for 1 h spinning time pore size was 231 µm and the same for 3.5 h was 4.1 µm. However, the number of pores increased with spinning time. The results confirmed adhesion of MC3T3-E1 cells on the SF sponge, SF nanofibers and SF three dimensional scaffolds. Higher cell adhesion was found on the three dimensional scaffold in comparison to the nanofibers and sponge, possibly due to highly porous structure with very small and numerous pores in the resultant composite; hence more cell adhesion sites. The cell adhesion result confirmed biocompatibility of the SF 3D-scaffold and hence its suitability for applications in tissue engineering.     

Fabrication of silver nanoparticle/polyvinyl alcohol/polycaprolactone hybrid nanofibers nonwovens by two-nozzle electrospinning for wound dressing

In this study, two biodegradable polymers, polycaprolactone (PCL) and polyvinyl alcohol (PVA) were used to fabricate nanofiber nonwovens (NFNs). Also, the silver nanoparticles (AgNPs) successfully reduced by using tea polyphenols (TP) and incorporated in the NFNs via electrospinning. The morphologies of the NFNs and AgNPs were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), respectively. The PCL nanofibers and PVA nanofibers interweaved each other, and AgNPs with average diameter 1.53±0.15 nm were embedded in the PVA nanofibers. The properties of electrospun NFNs were characterized by pore property, swelling/weight loss, water contact angle, mechanical property, and antibacterial activity. The nanofibers cross-linked to each other forming the 3Dnetwork porous structure with diameter about 1-1.5 μm. Although the hydrophobic PCL was added in the hybrid NFNs, the NFNs still showed hydrophilic propriety, high swelling degree (i.e. swelling degree is 330 % for 48 h), and low weight loss (i.e. weight loss is 22.4 % for 48 h). Also, the hybrid PCL/PVA/AgNPs NFNs exhibited a suitable mechanical property for wound dressings (i.e. tensile strength is 4.27 MPa, and breaking elongation is 88 %). Moreover, the hybrid NFNs effectively inhibited growth of Escherichia coli and Staphylococcus aureus. In summary, this PCL/PVA/AgNPs NFNs may provide a promising candidate for accelerating wound healing.     

SPI/PEO blended electrospun martrix for wound healing

Conventional textile based wound dressing materials are cost effective and highly absorbent, but when used alone fails to provide optimal wound healing conditions like homeostasis, non-adherence, maintenance of a moist wound bed, etc. Electrospun polymer web meets the requirements outlined for wound healing, by their microfibrous structures provide suitable environment for wound healing apart from the function of polymers. In this study, blends of soy protein isolate (SPI) and poly(ethylene oxide) (PEO) nano fiber web was prepared by electro spinning process. The developed blended nano fiber web was subjected to SEM, FTIR to evaluate fiber size and functional properties respectively. The Moisture vapour transmission rate (MVTR) result shows the blended electrospun web gives suitable mosit environment over wound bed such as the MVTR is 2994 g/m²/day. The blended electrospun web gives positive result on antimicrobial activity. The effect of SPI/PEO blended electrospun web on wound healing was experimented with female wistar rats and the blended electrospun web shows excellent result on wound healing by the growth of new epithelium without any significant adverse reaction. Forming of SPI/PEO electrospun fiber was fulfilled many critical elements desirable in a wound material.     

Electrospinning of <Emphasis Type="Italic">Bombyx mori</Emphasis> silk fibroin nanofiber mats reinforced by cellulose nanowhiskers

Cellulose nanowhisker (CNW) reinforced electrospun Bombyx mori silk fibroin (SF) nanofibers were fabricated. The morphology, structure, and mechanical properties of nanofibers were investigated by FE-SEM, TEM, FTIR, and tensile testing. It was found that the nanofiber size decreased obviously from 250 nm in the unreinforced mat to 77–160 nm in the CNW reinforced mats depending on the CNW content due to the increased conductivity of spinning dope. In the reinforced mats, the CNWs were embedded in the SF matrix separated from each other, and aligned along the fiber axis. There was a positive correlation between the CNW content and the tensile strength and Young’s modulus of reinforced mats. However the strain at break dropped gradually with the increase of CNW. When the CNW content was 2 w/w%, the tensile strength and Young’s modulus of reinforced SF nanofiber mats were about 2 times higher than those of unreinforced mat.     

Grafting of tyrosine-containing peptide onto silk fibroin membrane for improving enzymatic reactivity

During enzymatic modifications of silk fibroins, the accessibility of tyrosinases to the reactive sites was limited owing to the steric hindrance of tyrosine residues in the fibroin proteins. To improve the reactivity of silk fibroin, a tyrosine-containing peptide (TyrP) was covalently grafted onto the fibroin surfaces using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Enzymatic oxidation of the modified fibroins was subsequently carried out with a mushroom tyrosinase, followed by coupling of ε-polylysine (ε-PL) with the generated o-quinone residues of silk fibroins. The efficacy of grafting reaction was examined by means of SDS-PAGE and amine acid analysis. The results indicated EDC treatment might cause the direct self-crosslinks of silk fibroins and TyrP-bridged cross-links of fibroin molecules as well, which led to a noticeable increase in the molecular weight of fibroin proteins. TyrP-grafted fibroins displayed higher reactivity compared to the untreated, and more ε-PL was bonded to the fibroin surfaces when incubating with tyrosinase, resulting in improved wettability and mechanical property. The presented work offers an efficient alternative for the enzymatic modification of the fibroin-based materials with tyrosinase.